I. Field
The following description relates generally to wireless communications, and, amongst other things, to seamless inter-frequency handoff in wireless communication networks.
II. Background
Wireless networking systems have become a prevalent means by which a large number of people worldwide communicate. Wireless communication devices have become smaller and more powerful to meet consumer needs, which include improved portability and convenience. Users have found many uses for wireless communication devices, such as cellular telephones, personal digital assistants (PDAs) and the like, and demand reliable service and expanded coverage areas.
To effectuate continued coverage for mobile stations, access points (base stations, access networks, etc.) associated with cellular networks are geographically positioned so as users change location they do not lose services. Thus, mobile stations can be “handed off” from a first base station to a second base station. In other words, a mobile station will be serviced by a first base station while in a geographic region associated with such base station. When the mobile station is transported to a region associated with a second base station, the mobile station will be handed off from the first base station to the second base station. Ideally, the handoff occurs without data loss, loss of service, and the like.
Conventionally, this handoff occurred through a significant amount of messaging between mobile stations and base stations. For instance, as a mobile station was transported toward a base station, various messages were delivered between the mobile station and the base station, as well as between the base station and a base station currently servicing the mobile station. This messaging enables assignment of forward link and reverse link channels to be made between the mobile station and the base stations. To enable a handoff to occur quickly and without loss of a substantial amount of data, a set of base stations can be prepared to provide services to the mobile station.
This set of base stations can be updated as the geographic region associated with the mobile station is altered. In more detail, the mobile station can be adapted to monitor for communications or receive communications over a first frequency from a first base station. A second base station can communicate with the mobile station over the same frequency, and the second base station can be added to the set of base stations if particular performance parameters are met. Once the base station is added to the set, it is prepared to service the mobile station once it enters a particular geographic range of such base station. The handoff between base stations occurs expediently as well as without loss of any significant amount of data.
Transferring or handing off to another sector operating at the same frequency is common and can be performed utilizing existing techniques. However, handing off frequencies between sectors, or inter-frequency is typically achieved using a hard handoff in which probability of loss of data and loss of connection is higher. Inter-frequency handoff includes handing off between systems of the same technology but over different frequencies. A network deployment needs inter-frequency handoff for various business reasons, such as availability of spectrum and frequency reuse factor. In such a deployment, there is a need for a seamless inter-frequency handoff. Therefore, to address the aforementioned, there is a need for techniques to facilitate seamless inter-frequency handoffs to improve communication and efficiency in wireless network systems.